Great films have a thousand component parts. But if there’s any doubt that a stellar cast and sharp script are a film’s most indispensable ingredients, a quick viewing of writer/director Sally Potter’s biting and play-like The Party will cement the case.

And it will be a quick viewing: at just 71 minutes, The Party gets right to the point. Charismatic Janet (Kristin Scott Thomas) is ascending the ranks of Britain’s National Health Service. The newly minted minister is hosting a celebratory dinner at the comfortable London home she shares with husband Bill (Timothy Spall).

Acerbic fun in The Party.

As the film opens, Janet is preparing food in her kitchen — and fielding congratulatory calls on her mobile — while an apparently shell-shocked Bill cranks vinyl and glugs wine in the living room. These two are clearly not on the same page… and some of those calls Janet is getting seem very intimate.

But there’s no time to ponder this emotional gulf. In walks the evening’s first arrivals, Janet’s acerbic best friend April (Patricia Clarkson) and her platitude-spouting partner Gottfried (Bruno Ganz), clearly a yin and yang of naked cynicism and gentleness.

Next through the door is lesbian couple Martha and Jinny (Cherry Jones and Emily Mortimer) followed finally by Tom (Cillian Murphy), husband to Janet’s closest ministerial aid who is running late. Though they inevitably scan as somewhat one-dimensional, each swiftly developed character (smug Martha, gentle Gottfried, erratic Tom) serve as catalysts, allowing what happens next to charge like greased lightning. Before the first bottle of bubbly is drained, spontaneous announcements beget searing confessions, all leading to disastrous behaviour.

It’s quite a trip, and one well abetted by suspension of disbelief, though rewarded with some outstanding zingers (mostly delivered by Clarkson’s character) and a thrilling sense that absolutely anything can happen despite the ostensible camaraderie of these souls.

Potter — maybe best known for 1992’s remarkable Orlando with Tilda Swinton — shot The Party in black and white which, combined with its simple setting (three rooms and small back garden) underscores the urgency of the storyline and keep us fixed on each character as they slowly unravel, savagely yanking each other down with them.

Comparisons to Roman Polanski’s Carnage from 2011 seem inevitable but there are worse things one can think of for a film powered almost entirely by dialogue and, eventually, by the one character absent from the dinner party. All that, and a twist ending. This is a movie about searing characters spouting piercing lines. Films this trenchant (and mercifully short) don’t come along every day.